An observational study from researchers at the Jean Mayer USDA Human Nutrition Research Center on Aging looked at data from 549 men and women enrolled in an aspect of the Framingham Heart Study, focusing on scores on the Mini-Mental State Examination (MMSE). The MMSE is a list of questions and tasks commonly used to screen for dementia.
The subjects were then divided up into five groups based on their levels of vitamin B-12. They were then screened on the MMSE five times over eight years. The two groups with the lowest levels of vitamin B-12 were associated with a faster cognitive decline than the other groups. The men and women in the second lowest group did not fare any better in the MMSE scores than those with the worst levels of vitamin B-12 in their blood.
It had been well established previously that a severe vitamin B-12 deficiency led to much faster rates of cognitive decline. However, this new study suggests that even a mildly low-level of vitamin B-12 could be an influencing factor in cognitive decline. This could suggest that a deficiency in the vitamin could be affecting far more elderly people than was previous realised.
The test subjects were mainly women who had earned at least a high school diploma. As such, the researchers suggested that research into a broader range of the population would be required to see if the resulting deficiency in vitamin B-12 produced a similar effect.